Forbes' latest listing of the world's billionaires puts Mexico's Carlos Slim Helu and family again on top, with a net worth of $69 billion.

Slim's self-made fortune comes from telecommunications. The 72-year-old is chairman of Mexico's Telmex. His fortune is down $5 billion from last year, says Forbes, owing to a decline in the share price of America Movil, another telecom company that accounts for more than half of Slim's net worth.

Bill Gates and Warren Buffett of the U.S., who respectively have $61 billion and $44 billion, are next on Forbes' list. Gates' fortune comes from Microsoft, the software giant that he founded. Buffett's comes from investment giant Berkshire Hathaway.

This year's list netted more billionaires than ever before: 1,226 people worth a record $4.6 trillion collectively.

The richest newcomer is Colombia's Alejandro Santo Domingo Davila, described by Forbes as a 35-year-old bachelor living in New York City, who took over his father's beer empire after his October 2011 death. His wealth: $9.5 billion.